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Anthropologists once thought that the ancestors of modern [#permalink]

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21 Dec 2011, 14:41

Question 1

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Question Stats:

45%(02:36) correct55%(01:57)wrongbased on60

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Question 2

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Question Stats:

56%(00:30) correct44%(00:31)wrongbased on63

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Question 3

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Question Stats:

48%(00:15) correct52%(00:24)wrongbased on66

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Question 4

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Question Stats:

40%(01:07) correct60%(00:17)wrongbased on65

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Anthropologists once thought that the ancestors of modern humans began to walk upright because it freed their hands to use stone tools, which they had begun to make as the species evolved a brain of increased size and mental capacity. But discoveries of the three-million-year-old fossilized remains of our hominid ancestor Australopithecus have yielded substantial anatomical evidence that upright walking appeared prior to the dramatic enlargement of the brain and the development of stone tools.

Walking on two legs in an upright posture (bipedal locomotion) is a less efficient proposition than walking on all fours (quadrupedal locomotion) because several muscle groups that the quadruped uses for propulsion must instead to (?) provide the biped with stability and control. The shape and configuration of various bones must likewise be modified to allow the muscles to perform these functions in upright walking. Reconstruction of the pelvis (hipbones) and femur (thighbone) of “Lucy”, a three-million-year-old skeleton that is the most complete fossilized skeleton from the australopithecine era, has shown that they are much more like the corresponding bones of the modern human than like those of the most closely related living primate, the quadrupedal chimpanzee. Lucy’s wide, shallow pelvis is actually better suited to bipedal walking than is the rounder, bowl-like pelvis of the modern human, which (?) evolved to form the larger birth canal needed to accommodate the head of a large-brained human infant. By contrast, the head of Lucy’s baby could have been no larger than that of a baby chimpanzee.

If the small-brained australopithecines were not toolmakers, what evolutionary advantage did they gain by walking upright? (Line 50) One theory is that bipedality evolved in conjunction with the nuclear family: monogamous parents cooperating to care for their offspring. Walking upright permitted the father to use his hands to gather food and carry it to his mate from a distance, allowing the mother to devote more time and energy to nurturing and protecting their children. According to this view, the transition to bipedal walking may have occurred as long as ten million years ago, at the time of the earliest hominids, making it a crucial initiating event in human evolution.

20: the passage suggests that proponents of the theory mentioned in lines 50-54 (One theory is … offspring) assume that which of the following steps in human evolution occurred most recently?

A: development of a nuclear family structure B: transition from walking on all fours to walking upright C: dramatic enlargement of the brain D: use of the hands to gather and carry food E: modification of propulsive muscles to provide stability and control in locomotion

21: the passage suggests that, in comparison with the hominid australopithecines, modern humans are

A: less well adapted to large group cooperationB: less well adapted to walking upright C: more agile in running and climbing D: more well suited to a nuclear family structure E: more well suited to cooperative caring for their offspring

22: According to the passage, the hominid australopithecine most closely resembled a modern human with respect to which of the following characteristics?

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Re: Anthropologists once thought that the ancestors of modern [#permalink]

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22 Jan 2012, 05:35

Question 20 : C

The last paragraph suggest that the human started to walk upright before it developed large brain It suggests the reason for walking upright as (1) nuclear family, (2)male collecting food using 2 hands. That understanding puts those options chronologically behind the development of large brain.

The last options remaining suggests the modifications of muscle as transition from walking on four feet to walking on 2 feet. We can associate this phase also to walking upright phase.... Thus answer C

Re: Anthropologists once thought that the ancestors of modern [#permalink]

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22 Jan 2012, 05:40

Q21: B

Q 22: There are two options that are close

Shape of pelvis and method of locomotion. I think C is a trap, this choice is obviously discussed on the second para. How ever the passage also suggests that the pelvic bone in modern humans evolved to accommodate children with large brains. SO there is some difference

Re: Anthropologists once thought that the ancestors of modern [#permalink]

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27 Aug 2017, 07:37

YangYichen wrote:

can someone help shed some light on Q22 why C is wrong?

Hi YangYichen

Q22 We have to answer which characteristic is similar in both modern human beings and hominid australopithecineAs per the passage there is only one characteristic that was same in both i.e walking upright .

"Lucy’s wide, shallow pelvis is actually better suited to bipedal walking than is the rounder, bowl-like pelvis of the modern human, which (?) evolved to form the larger birth canal needed to accommodate the head of a large-brained human infant. By contrast, the head of Lucy’s baby could have been no larger than that of a baby chimpanzee."

C is a difference not a similarity Hope it helps
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Re: Anthropologists once thought that the ancestors of modern [#permalink]

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28 Aug 2017, 03:59

arvind910619 wrote:

YangYichen wrote:

can someone help shed some light on Q22 why C is wrong?

Hi YangYichen

Q22 We have to answer which characteristic is similar in both modern human beings and hominid australopithecineAs per the passage there is only one characteristic that was same in both i.e walking upright .

"Lucy’s wide, shallow pelvis is actually better suited to bipedal walking than is the rounder, bowl-like pelvis of the modern human, which (?) evolved to form the larger birth canal needed to accommodate the head of a large-brained human infant. By contrast, the head of Lucy’s baby could have been no larger than that of a baby chimpanzee."

C is a difference not a similarity Hope it helps

i c the referred sentances indicating the right answer~thx a lot~
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